Tag Archives: satellite tracking

I don’t recall having seen a cuckoo before, even though I’ve heard their unique call many times. But on my sojourn over to Wicken Fen a couple of weeks ago there were lots of them. ‘Lots‘ is a relative term because cuckoos are becoming increasingly scarce, their conservation status is red due to recent declines in the breeding population and in 2000 there were 9.6-19000 breeding pairs in the UK. But on this trip we heard and saw at least 5 and possibly several more.

Just before I spotted the first cuckoo I glanced across the lake and this was the view:

A pair of shoveler in the foreground, a little egret behind and a roe deer just beyond the reeds

I really like this picture because of the colours of the reeds and the water in the evening sunshine, but also because it contains three interesting species. Apart from rabbits, any wild mammal is exciting to see in this country, so the roe deer was a pleasing encounter. The little egret (Egretta garzetta, Dansk: silkehejre) is a member of the heron family which is now resident in the UK, presumably as a result of climate change. I associate them with warmer places because that’s where I saw them before 2000, but nowadays they’re not particularly uncommon here. And in the forefround are two shoveler (Anas clypeata, Dansk: skeand) which are migrant visitors to the UK, but this pair obviously liked it enough to linger and are still here in the middle of May, long after they would normally have left.

And then there were the cuckoos:

A pair of cuckoo, Cuculus canorus, Dansk:gøg

The cuckoo is an incredible bird and until very recently it was poorly understood. Last year the British Trust for Ornithology (BTO) managed to tag five male cuckoos with tiny satellite tracking devices and found out that they headed to the tropical sub-Saharan rainforests of Cameroon and the Democratic Republic of Congo. The cuckoo arrives back in England from Africa in late March or April and departs in July or August. It leaves earlier than other species because its parasitic breeding strategy removes the need for chick rearing. That means the cuckoo spends a minimum of 8 months a year in Africa so to call it a British bird is, I suppose, less than accurate, even though it breeds here.

The classic hanging wings pose which I always associate with the cuckoo

The tagged birds were all fitted with solar powered devices which transmit location data once every 48hr. The tracking data revealed that all five birds headed south over France and across the Mediterranean before heading down across Africa to Cameroon and DRC. All five made it. One of the birds died in Cameroon and two more died on the way back, but two of the five made it back to East Anglia this year. I believe the BTO plan to tag more birds including females and I’m very keen to see the results of that experiment.

The cuckoo is an iconic bird in the UK and it’s call is very distinctive. The call is generally recognised as a signal that Spring has arrived and there are local traditions around the UK based on the cuckoo. It is said in Worcestershire that the cuckoo is never heard before Tenbury Fair on April 21st or after Pershore Fair on June 26th. The song actually changes in June from the characteristic ‘cuck-coo‘ song to a shortened ‘cuck‘, and there is a rhyme about this:

In April I open my bill In May I sing night and day In June I change my tune In July far far I fly In August away I must

My Dad remembers a similar rhyme he used to sing when he was a kid in the 1940’s which was essentially the same but with some local Northamptonshire words substituted in.

I’m not quite sure what these two were doing but they were acting as a pair, and every minute or two one of them would dive off into the adjacent reedbeds to return a minute or so later. As I mentioned above, cuckoos are parasites and they could have been looking for nests to parasitise. There breeding strategy is unique, at least as far as I know. They lay their eggs in the nests of one of three other small songbird species: the reed warbler, the meadow pippit and the dunnock. All of these are the size of a sparrow (ish) so are much smaller than the cuckoo which is dove-sized, which I guess guarantees that the cuckoo chick will be much bigger than its ‘siblings’ and it won’t be threatened. The cuckoo chick then ejects the other chicks from the nest to die and the parents assume it is one of their own and feed it until it fledges. I’ve seen film of a cuckoo chick turfing out the other chicks and it’s a remarkable process, and not particularly pleasant to watch!

Despite their unsavoury procreation habits they are spectacular and charismatic birds and I hope the BTO research can find ways to guarantee their continued return here to brighten up the Spring and Summer.